Wikipedia:Selected anniversaries/April 20
April 20: Festival of Matsu in Southeast Asia (2006), Ridván begins at sunset in Bahá'í Faith.
- 1653 - Oliver Cromwell dissolved the Rump Parliament of the Commonwealth of England.
- 1862 - Louis Pasteur (pictured) and Claude Bernard completed the first test on pasteurization.
- 1914 - A fire and a gun battle between the National Guard and striking coal miners in Colorado led to 17 deaths in the Ludlow massacre.
- 1968 - Pierre Trudeau succeeded Lester B. Pearson as Prime Minister of Canada.
- 1999 - Eric Harris and Dylan Klebold murdered 13 people in the Columbine High School massacre.